Heretofore, self-cooling beverage containers have not met with widespread commercial success owing to a variety of design deficiencies. Complexity of design structure has rendered many known devices as impractical. Safety, in some cases, has presented a concern. The opportunity for contact between the refrigerant and beverage creates a risk of altering beverage quality at best and toxicity to the consumer at worst. Further, other known devices wherein the refrigerant is vented in association with the tab opening of the container presented a serious safety hazard. When vented, the evaporating refrigerant was expelled upwards towards the face of the consumer with liquid particles of refrigerant being borne within the refrigerant vapor. This problem was addressed in U.S. Pat. No. 3,852,975 to Beck which teaches a container provided with a safety shield to protect the consumer from the upwardly expelled spray. Inefficiency of refrigeration and/or environmental concerns have been other deficiencies of known devices.
U.S. Pat. No. 5,214,933 discloses a beverage container of conventional exterior dimensions, readily adaptable to existing packaging, stacking, transporting and handling needs. An upper chamber containing the beverage to be cooled is axially provided with a discrete refrigerant chamber affixed to the base of the upper chamber and extending at least partially into the upper chamber. The interior region of the refrigerant chamber is fluidicly isolated from the interior region of the upper chamber.
The pressurized refrigerant chamber contains an environmentally friendly refrigerant of a determined quantity in liquid form and is provided at its lower end by a sealed aperture integral with the base of the upper chamber.
A third chamber serves several functions. Firstly, it provides a means for conveniently venting the refrigerant chamber by delivering a seal opening member to the sealed aperture. Secondly, it provides a venting chamber, or refrigerant dispersal assembly, wherein the volatile evaporating refrigerant is vented and decelerated, thus eliminating the risk of a blast of spray being directed at the consumer. Further, the third chamber increases refrigeration efficiency by maximizing the surface area of cooling to include not only the refrigerant chamber, but also the lower portion of the surface of the upper beverage container. This third unpressurized chamber may be formed as a separate generally cup-shaped cap in preferably threaded engagement to the base of the upper chamber. The inner surface of the base of the cap is further provided with a seal opening member (for example, a perforation member) spaced in alignment with the sealed aperture. Rotation of the cap in threaded engagement with the upper chamber results in an upward movement of the perforation member which perforates the seal of the aperture of the refrigeration chamber, thus venting and dispersing the evaporating refrigerant into the third chamber at atmospheric pressure. The ensuing cooling effect of evaporation and the adiabatic expansion of refrigerant vapor cools the walls of the refrigerant chamber and the base of the upper chamber, cooling the beverage by thermal conduction.
In an alternative embodiment, the upward movement of the seal opening member may be facilitated by a bead-and-groove engagement between the cap and the exterior wall of the upper chamber.
In a further embodiment, the base of the cap may be provided as to be sufficiently flexible to permit upward displacement of the seal opening member by upward manipulation of the cap base as a means of venting the refrigerant.
As noted above, the embodiments disclosed in U.S. Pat. No. 5,214,933 incorporated a discrete refrigerant chamber that is affixed to the base of the upper chamber. With this configuration, the manufacturing cost of the beverage container is relatively high; the high cost is due to the requirement for separately fabricating, storing, and assembling the composite refrigerant chamber/top chamber assembly.
Moreover, the refrigerant chamber, as disclosed in U.S. Pat. No. 5,214,933 has a relatively narrow mouth (which is covered by sealing element 32). As a consequence, filling of the refrigerant chamber during manufacture is best performed by injection, again a relatively costly process. Accordingly, the beverage containers disclosed in U.S. Pat. No. 5,214,933 are complex multi-element structures that are relatively costly to manufacture.